This invention relates to a device for generating high frequency signals such as microwave or milliwave signals and particularly to a method of controlling an output of a high frequency generator, including miltiplier means, having diodes, within the output of the generator.
High frequency generators, generators used for obtaining predetermined frequency signals by multiplying the outputs from a high frequency oscillator comprising a frequency stabilizing circuit such as Phase Lock Loop (PLL), are known. The high frequency generating means is required to turn the output off for a while after the power switch is turned on, because an abnormal frequency may be generated up until the frequency stabilization reaches a steady state due to the operation of a frequency stabilizing circuit.
The output of a high frequency generating means is turned off by the following methods: first, an ON/OFF circuit, such as diode switch using a PIN diode or coaxial relay, is inserted into the output and second, an output is turned off through suspension of operation by changing the bias of an amplifier used in the output circuit. The former method has a disadvantage in that the circuit structure is complicated because an ON/OFF circuit is added and moreover signal loss therein is inevitable. The latter method cannot be applied in a device not having an amplifier. In both of these methods, the output is turned off in the output frequency stage and shielding must be taken into account in order to obtain a large attenuation of the output, resulting in an increase in the device cost.